Make sure each identifier_number in the CSV belongs to one third_party with the same name and identifier_type.
Here you can find the template:
Create a CSV file with the next structure, be sure set the separator with a comma (,).
The type of the third_party is passed as URL param.
For demo account users it is advisable to create a small number of customers and suppliers manually in the frontend to simplify the testing of PULPO WMS.